Shooting the Girardoni

With all new guns comes tuning for performance and efficiency. Various factors effect the tune, some fixed, others variable.

This is a 6X6 Douglas fir post with numerous balls fired from 25 yards.

The impact energy is sufficient to fuse balls together.

Valve orifice diameter is a variable which effects gas flow. As can be seen above, it is directly proportional to power (FPE) and and inversely to efficiency (FPE/CI). The efficiency is how much power per volume of air at STP can be obtained.

The valve spring slows the opening and speeds the closing of the valve. Many have theorized that an airgun could be operated with no spring. This graph shows that to be true. However, the power goes up disproportionately to the amount of air consumed per shot, hence the efficiency is almost half without the spring.

The type, diameter and preparation of the lead ball have effects on performance. All rounds shown are 100% lead. The difference of .003″ is negligible between the .457 and .460 rounds. The Swaged balls seem harder and have a pronounced decrease in performance. Also note that the unlubed balls are more erratic and even lesser in performance.